Treatment of starch hydrolyzates with



U it d S a e Pat TREATMENT OF STARCH HYDROLYZATES WITH FORMALDEHYDE UNDER CAREFULLY CON- TROLLED CONDITIONS Harry W. Durand, Glenshaw, Pa., assignor to Corn Products Refining Company, ew York, N. Y., a corporation of New Jersey No Drawing. Application October 19, 1953 Serial No. 387,039

3 Claims. (Cl. 260-2333) This invention relates to a process for producing from starch hydrolyzates new materials suitable for use as adhesives, sizes, thickening agents, colloid stabilizers and the like. a

In U. S. Patent 2,563,014, August 7, 1951, is described a method for producing polymerized carbohydrate materials which have improved properties over previously known dextn'n products. However, although such products are superior to any others available, they do lack certain desirable properties. For example, such products when dissolved in water form thin sirups unless the solids content is unusually high. It is not possible to obtain from them pastes with high viscosity at low solids concentration. Regardless of the solids content of the pastes except above 60 to 65 percent, the pastes will be thin, and, of course, cannot be used in certain applications where a thick bodied paste at low solids is required. Thus the method of U. S. Patent 2,563,014 lacks a means of producing materials the viscosity of which can be adjusted over a wide range in addition to the other desired characteristics.

Accordingly, it is an object of this invention to provide a novel adhesive having a wide range of viscosity characteristics and a method for making the same. A further object is to prepare a novel carbohydrate material from starch hydrolyzates. Still a further object is to provide a new method for polymerization of carbohydrate derivatives wherein the degree of polymerization and likewise the properties of the resultant product are adjustable over a wide range. Other objects will appear hereinafter.

I have discovered that these objects may be accomplished by treating starch hydrolyzates with formaldehyde under carefully controlled conditions. The present invention comprises heating dehydrated starch hydrolyzate in contact with formaldeyde under conditions conducive to polymerization.

In carrying out the invention a starch hydrolyzate is prepared in conventional manner, as by acid hydrolysis or enzyme hydrolysis, the former being preferred. The D. E., i. e., percent of reducing sugar, calculated as dextrose, dry basis, should be within the range of about 5 to 40, preferably about 15 to 20. If the D. E. value is below about 15 percent there will be residual starch material present which will exhibit undersirable retrogradative effects, but if this material is removed from the hydrolyzate, as by filtration, prior to polymerization, the

2,836,591 C Patented Ma 27, 1958 resulant product will be satisfactory. After the pH of the hydrolyzate has been adjusted to 4.5 to 5.5, purified and concentrated to about 25 to 28 B. in conventional manher, then sufficient commercial 37 percent aqueous formaldehyde to give up to about 2 percent formaldehyde (calculated as anhydrous aldehyde, based on the dried substance) is added and the resultant mixture dehydrated in any suitable manner, as by spray drying, vacuum drying and the like, until the moisture content has been reduced to an amount below about 10 percent, about 2 to about 7 percent being satisfactory. Alternatively, the formaldehyde may be added subsequent to drying in which case it is preferred to use the powdered polymeric form referred to as paraformaldehyde or polyoxymethylene.

The pH of the material undergoing polymerization should be within the range of about 1.5 to 4.5 (determined on 10 percent aqueous solution of the material) during the polymerization. The adjustment of the pH may be made with various acidic materials, e. g., phosphoric acid, hydrochloric acid, boric acid, acid liberating salts, e. g., aluminum chloride hexahydrate. Phosphoric and hydrochloric acids are preferred. The adjustment of the pH may be made after the concentration step and either before or after the dehydration step.

The temperature at which the polymerization reaction proceeds must be carefully regulated to assure the proper rate of polymerization and water formation. Temperature regulation is necessary in order to permit the water, which is formed as the result of the chemical condensation involved, to be continuously removed. The absence of such regulation may result in the interference with polymerization by side reactions, such as hydrolysis and caramelization, resulting from the presence of excessive moisture in the reaction mixture.

Among the types of equipment which may be used for effecting polymerization are heat-jacketed kettles, commonly employed in the commercial manufacture of torrefaction dextrins, tray driers, conveyor belt driers and the like. While the temperature and time cycles will be somewhat variable, depending on the particular characteristics of equipment used, generally, it will be found most satisfactory to carry out polymerization within a temperature range of from about 100 C. to about 200 C. At lower temperature than these the polymerization reaction appears to proceed very slowly under the previously specified pH conditions, whereas higher temperatures promote a tendency toward color formation, caramelization and other undesirable side effects. In some cases, it may be desirable to start polymerization at a lower temperature, say at C. to C., in order first to remove residual moisture from the product. Such a predrying step minimizes any tendency for the product to lump or fuse on' subsequent application of higher temperatures.

In the matter of color formation tendency at high temperatures, it has been observed that the presence of the added formaldehyde has a beneficial effect in that a much lower color is obtainable with a given viscosity increase than is normally obtained in cases employing no formab dehyde.

7 subject to the type of equipment used. Due to the complexity of the situation, it is in fact not feasible to attempt to set forth the exact operating conditions for each product possible of production. The above description assess;

gaseous hydrochloric acid to a pH of 2.5 as measured on an aqueous solution containing 10 percent solids and subjected to heating in a dextrin cooker of laboratory size and design, with constant speed (75 R. P. M.) rotary agitation. temperatures ranging from about 100'C. at the start to 145 C. for the last 3 hours.

' V 1 on in Table I.

TABLE 1 Run Nn 128-103 128-102B 149-8 149-9 (Control) Starting Sir p; a V "Total siru solids, D. B. (percentL..- 47.5 47.4 47. i Feririalde yde content, D. B. (pcrcen eulatcd None 0. 8 1. 1. By analysis- 0.78 0.95 v 1; Sir-up pH u 4.5 4.5 r 4.5 .4. Spray Dried Product:

D. '13., D. 13. (percent) 18.5 18.5 18.6 18. H at 10% solids 4. 4. 3 4.3 V 4. Solubles (percent)- 100 100 100 100 Moisture content" p 6. 5 5.0 4. 2 3. Formaldehyde content, D. B. (percent) 0.70 0. 85 l. Based on starting concn (percent) 89. 7 S9. 5 s4. Polymerized Product: Initial pH at 10% solids 2. 5 2. 5 2. 5 2. Final pH at 10% solids. 3. 3 3. r 3. 6 3. D. E. (percent) 5.9 7.6 9. 1 9. Sclubles (percent) 100 100 V 100 93 Viscosity of aq. soln.

at 10% solids, Ostwald (cp 1. 76 2. 28 2. 66 1 2. 6 at solids, Gardner (po1ses) 12 46 60 1 150 Color at 60% solids (Helligelnn. 13 9 8 8 Fbrmaldehyde content, D. B. (percent)-- 0 62 0. 0.92 Based on starting conc'n (percent)-.- 79 78 i1 viscosity oi starting sirup solids before polymerizatio i Insolubles remoyed. i f Insolubles not removed.

and exampl s to be ven ubs quently will enab pe skilled in the to select the, conditions of treatment best suited to obtain the products they desire.

The above process permits production of polysaccharidesco'vering a wide range of viscosity and solubility. De

pending on the D. E. of the starch hydrolyzate and amount 7 of formaldehyde used, products can berna de, on the one hand, having high viscosity, with complete or partial'solubility, and, on the otherhandg'possessing relat yf o i'iscosifis with. ubsta tia l c mplete solubily- T p o r i s of he :fotntcr type sug t u a in applications concerned primarily with colloid stabilization, h ck nin effect S zes. and th like; he a yp v ppe inen ly su t d't orapplica ji i the Watersoluble adhesive fild 9? Such uses as paper lamination,

remoistening adhesives, and the like.

The following examples are merely illustrative of the adaptability of the subject process in connection-and a are not intended to be limiting in any sen e,

. EXAMP Polymerization at difiefent levels of formaldehyde 7 concentration A corn starch conversion sirup having a rated D. E;

of 16 to 20 percent and of approximately 50 percent solids content was split into 4 batches. Tothree of these was added suflicient commercial iiqrmalin (37 percent aque-- Gil The formaldehyde modified products without exception gave systems ofpe rjmanenhhigh clarity and excellent flow, subsequent to hot dispersion in water to 60 percent solids. Solution length was considerably improved over that of the unmodified control. No tendency was observed for any ofthe high solids systems so prepared to thicken r hin o on t r ge. or to det lcpany m nif st tion of insolubility. V

T p lyme ized Produc w r co t d atol pe en ol ds a d 1 0 Pe c nt rag bend p per sto k andtes ecl for hesi on mois e n ol ow d by' pp a ion o h mois c ed a n s. tou coa cd stock.- Rat 'of t s de e opmen and d sr cicf final co e vene s obtaine were observed to be directly in line with the degree of i cos ty modification ob ained A lcf: the o mald hy mcdifie 'p o uc s Wereh ly mpro ed in thes e pec o e h C nt o unmodified p oduct. EX M LE I1 Efiect of polymerization temperature a}; degiiee of formaldehyde modification Spray vdried corn sirup was redissolved in waterto make a sirup of roughly 50 percent solidsi T 0 this was added sufiicient 37 percent aqueous formaldehyde to give a calculated concentration of 0.8 percent, on the dr/ basis. Th re ultin s un s h n sp ried i h n' e as descr bed n Examp e I- h f llo in data relate to the starting sirup and the spray dried product therefrom: a

S'olubles (percent) can"; i Viscosity at 10% concn (cp.) 1.64 Formaldehyde contenL D. B. (percent)- The cycle used was 4 hours at cooker jacket The results are summarized Total sirup solids,jD. B. (percent) 'i; 48.0

asse sor Spray dried product:

D. E., D. B. (percent) 17.3 pH at 10% solids 4.7 Solubles (percent) 99.6 Moisture content (percent) 4.6 Formaldehyde content, D. B. (percent) 0.77

Samples of the spray dried product were blended with gaseous hydrochloric acid at a pH of 2.5 at 10 percent solids and subjected to heating in the laboratory dextrin cooker, described in Example I above, using the conditions of 4 hours at jacket temperatures of 145, 160 and 175 C. The results of these runs are summarized in Table II.

Based on starting concn (percent) In addition to the difierence in properties" between the products similarly derived from the corresponding start TABLE II Run N 149-28 149-29 149-80 Jacket temperature of cooker 0.)- 175=t=2 pH at solids:

initial 2.5. final 3.7. D. E. (percent)-.- 4.8. Solubles (percent)... Q9 81. VBcosity:

at 10% solids, Ostwald (cp.) 3.6 (llnsolubles removed.) at higher solids, Gardner (poises) g 9?f? f i1:: }No flow 25%. g g iii gggg Color (Hellige) 6 at 60% solids. 7 at 40% solids- 7 at solids. Formaldehyde content, D. B. (percent). 0.75 0.72 0.70.

Based on starting concn (percent)... 90 83.

In high solids (40 percent or above) aqueous solution, prepared using heat to obtain dispersion, all of the products listed gave homogeneous, perfectly clear and highly viscous systems. At concentrations of '20 to percent, products 149-29 and 14930 gave translucent, thixotropic jellies, showing substantially no tendency toward surface skin formation. At 60 percent solids, product 149-28 showed no tendency to thicken or gel on standing, and, as applied to 100 percent rag bond paper, was indicated to have excellent properties as a remoistening or laminating adhesive.

EXAMPLE H1 Two corn starch conversion sirups (at 14.4 and 18.6 percent D. E. (D. 13.), respectively) were processedin accordance with the procedure described in Example 1 above, the amount of formaldehyde added in each case prior to spray drying being sufiicient to give a calculated 0.8 percent concentration (D. 33.). The results obtained are summarized in Table III.

TABLE III Run No 128-96 l28-l02il Starting Sirup:

D. E. of sirup solids, D. B. (percent) l4. 4 18. 6 Solubles of sirup solids (percent) 100 100 Viscosity of sirup solids at 10% concn (cp.).. 1. 69 1. 59 Formaldehyde content of sirup, D. B. (per- 0.76 0. 78 v 47. 7 47. 5 pH of strup 4:7 t. 5 Spray Dried Product:

D. E., D. B. (percent) 14.2 18.5 pH at 10% solids 4. 8 4. 3 Solubles (percent) 93:8 100 Moisture content (percent) r 5. 7 5.0 Formaldehyde content, D. B. (percent) 0.70 0.70 Based on starting concn (percent) 02.1 89. 7 Polymerized Product:

pH at 10% solidsinitial 2. 5 .2. 5 a1 3. 5 3. 4 D. E. (percent)-.. 4.4 7. 3 Solubles (percent) 88 100 Viscosity of centrifuged 10% soln. (cp.) 2. 32 2. 25 Formaldehyde content, D. B. (percent).. 0. 56 0. 60 Based on starting concn (percent) 74 77 ing sirups without formaldehydeaddition:

Both formaldehyde-modified products showed eflicient adhesiveness, with regard to lamination of 100 percent rag bond paper stock, whereas the corresponding control products did not give a satisfactory bond.

EXAMPLE IV in this example, phosphoric acid was used as catalyst and was added to the starch hydrolyzates prior to spray drying. 20 percent were added to hot water to provide a sirup' containing 50 percent solids. To this sirup was added suflicient phosphoric acid to give a concentration of 0.5 percent (as anhydrous'HgPO based on the calculated corn sirup solids, together with sufficient water to compensate for evaporation loss. The acidified sirup having a pH of 1.8 was divided into six portions A, B, C, D, E, and F, to each of which was added sufficient aqueous formaldehyde (37%) to give the sirups a formaldehyde content, respectively, of 0.0, 0.25, 0.50, 0.75, 1.00 and 1.25 percent (asanhydrous formaldehyde, based on the calculated sirup solids). After standing at room temperature for 24 hours, the'samples were spray dried in a Bowen type drier in conventional manner. The dried samples were divided in half, except E and F, and then each sample was heated in a laboratory rotary cooker and polymerized. The conditions of the heat treatment and the analytical results obtained on the productsare summarized in Table IV. j

The data show thatloss of solubility begins when more than about 0.75 percent formaldehyde is used. Samples E and F, containing more than this, were not heated Spray dried corn 'sirup solids having a D. E. of

oss of solubility occurring at istemp ur r. I r o Formaldehyde modification appears to promote higher clarity fan'd'lower color; than obtained without such modification; Y

e r 7 above;145 C. because of I claim: 7 1

. 1. A process for producing :a carbohydrate material which comprises dehydratingma starch hydrolysis. liquor having a.D. E. valuefi'om about to about 40 to a moisture content below aboutilO percent,: heating the p c i TABLE IV pH at 10% solids HCHO content D. B. (percent)- Free (no hydrolysis) Total (after hydrolysis) Polymerization:

Temperature, O

T c After Polymerization:

pH at 10%,sollds, Final D. E HCHO content:

' Free";

Total Solubility (percent) Vi sc o sity at 72 F. '(poises) Brook- 67% solids 60% solids Color at 60% solids (Hellige) EXAMPLE v il-n'this enample boric acid was used as catalyst for polymerization. Corn siruphaving a D. E; of 40 percent and a density of 42 B. was diluted'to 50 percent solids.

' 'To this was added 6 percent of boric acid, based on the solids, and suflicient 37 percent aqueous formaldehyde to correspond to a 1.0 percent concentration (calculated as anhydrous formaldehyde, based on'the sirup solids) The mirtture was heated to dissolve. the boric acid and then allowed to stand for 48 hours at room temperature.

The sirup was spray dried using a pilot plant scale Bowen type drier with inlet temperature of about350" F The'spray dried product was then placed in a laboratory scale dextrin cooker employing a rotary agitator and subjected to polymerization using a'heating cycle of 4 hours.

atfa' maximum jacket temperature of 145 1 2 C.

' .iAnalytical data'pertaining to the products areas 'f ollhe pH was 4.3 on a 10 percent solution of the polymerized product. 7 f Theiprodu'ct polymerized in contact with formaldehyde has excellent solubilityand stability characteristics. How- Q ever, the adhesive and color properties are not qu'ite'as lows:

Formal- Viscosity dehyde D. E., at 67%' Content Solids and 7 D. 13. (Percent) 72 (Percent) (Poises) Spray dried product; 4..-- 0.92 42. 5 3. 7 Polymertzed product 10.84 22.6 31.5 Polymerized product, no formal- V dehydeu'"; V7 None 18.0 V 15 good as those ,of products obtained from corn sirup havingflower'D. E. values.

. While the process of our inventionfhas emphasized the use offcorn (maize) starch conversion sirup, other. starch conversion sirups, such as, for exa mple, grain sorghum,

good'results.

p otato,;rice, wheat, tapioca, may likewise be used with 1 dried product in contact with formaldehyde and in the presence of an acid catalyst at .a pH. of from about 1.5 toabout 4.5 and at a temperature betWeen,about'90,Q.

and 200 C. to polymerize componentsofsaid'producti the amount of formaldehyde 'not exceedingv about Zpercent calculated as anhydrous aldehyde based-on; the de- 1 hydrated substance. 1

2. A process for producing a carbohydrate material which comprises. dehydrating -a starch hydrolysis sirup;

having a D. E. value of about 20-and a 'pH value'of about 4.5 to 5.5 to a moisture content below about 10 percent, blending with thedn'ed product sufiicienthydrochloric acid to adjust the pH thereof to 2.5 andwith 1 percent of formaldehyde calculated as anhydrous alde-l hyde based on the dried su'bstance, and thereafter heating the mixture. at a temperature within the range of about of said product. I a

C. to C. thereby to polymerize components 3. A process for-producing a carbohydrate material, which comprises spray drying a starch hydrolysis liquor having a D. E. value of from about 5 'to about 40 con-. taining formaldehyde and phosphoric. acid,'to reduce the moisture content to below 10 percent, thereafterheating the dried mat'erialat aternperature nof'exceeding about 2005C. to'polymeriz e componentsof saidproduct; and continuous removing water formed by the polymerization reaction during the said heating'stepytheamount of formaldehyde not exceeding about 2 percent calculated as a'nhydrous aldehyde, based on the dried substance, and the pH of the liquor being about 1.5 toabout 4.5;

V 1 References Cited inithe file of this patent V UNITED STATES PATENTS 7 1,018,736 Alsleben l Feb. 27, 1912 7 2,510,748 Lolkema et a1. 1 lune o, 1950 7 2,563,014 Durand. Aug. 7, 1951 2,698,936 Staerkleet. al. Jan. 4,;1955

2,698,9 3? Staerkle etal. L Jan. 4, 

1. A PROCESS FOR PRODUCING A CARBOHYDRATE MATERIAL WHICH COMPRISES DEHYDRATING A STARCH HYDROLYSIS LIQUOR HAVING A D. E. VALUE FROM ABOUT 5 TO ABOUT 40 TO A MOISTURE CONTENT BELOW ABOUT 10 PERCENT, HEATING THE DRIED PRODUCT IN CONTACT WITH FORMALDEHYDE AND IN THE PRESENCE OF AN ACID CATALYST AT A PH OF FROM ABOUT 1.5 TO ABOUT 4.5 AND AT A TEMPERATURE BETWEEN ABOUT 90*C. AND 200*C. TO POLYMERIZE COMPONENTS OF SAID PRODUCT, THE AMOUNT OF FORMALDEHYDE NOT EXCEEDING ABOUT 2 PER CENT CALCULATED AS ANHYDROUS ALDEHYDE BASED ON THE DEHYDRATED SUBSTANCE. 